CN117231779A - Diaphragm type low-resistance backflow preventer - Google Patents

Abstract

The application relates to the field of valves, in particular to a diaphragm type low-resistance backflow preventer, which comprises a main valve body and a check valve body, wherein the check valve body comprises a cylinder body, a water inlet check valve plate and a water outlet check valve plate; the water outlet check valve plate is opposite to the liquid inlet and is in clearance fit with the inner wall of the cylinder body, a second spring is fixedly arranged between one end of the water outlet check valve plate, which is close to the supporting disc, and one end of the guide shaft, which is close to the water outlet cavity, and a second diaphragm is fixedly arranged between the outer surface of the water outlet check valve plate and one end of the cylinder body, which is close to the water outlet cavity, so that the water outlet check valve has the advantages of reducing the opening movement resistance of the movable check valve plate and preventing the check valve plate from being blocked and failing.

Description

Diaphragm type low-resistance backflow preventer

Technical Field

The application relates to the technical field of valves, in particular to a diaphragm type low-resistance backflow preventer.

Background

The low resistance backflow preventer is a check device which limits the pressure water in the pipeline to flow only in one direction, and consists of a secondary check valve and a water drain valve, wherein the secondary check valve is respectively opened when the water flows normally, the water drain valve is closed, the water smoothly flows through the backflow preventer, once backflow is generated (the outlet pressure is increased or the inlet pressure is reduced, and the inlet pressure is lower than the outlet pressure), the water drain valve is opened, the water in the middle cavity is emptied, so that air is blocked, and the downstream water is prevented from entering the upstream pipeline.

In the related art, the movable check valve plate of the low-resistance backflow preventer is sealed by adopting a sealing ring mode, on one hand, larger friction resistance exists when the check valve plate moves, so that the spring force of the return spring of the check valve plate is required to be larger, and further, the head loss is overlarge during normal operation; on the other hand, the sealing ring can cause the blocking of the check valve plate, so that the check valve group cannot be closed, the check failure is caused, and the medium backflow occurs.

Therefore, the applicant believes that the movable check valve plate is sealed by adopting a sealing ring mode, and the defects of overlarge resistance in the opening movement process and even check failure caused by the blocking of the check valve plate exist.

Disclosure of Invention

The application provides a diaphragm type low-resistance backflow preventer for reducing the opening movement resistance of a movable check valve plate and preventing the check valve plate from being blocked and invalid.

The technical aim of the application is realized by the following technical scheme:

a diaphragm type low resistance backflow preventer, comprising:

the main valve body is internally provided with a water inlet cavity, a middle cavity and a water outlet cavity which are communicated in sequence, and the cross section size of the middle cavity is larger than that of the water inlet cavity and the water outlet cavity;

the check valve body comprises a cylinder body, a water inlet check valve plate and a water outlet check valve plate, the cylinder body is arranged in the middle cavity, two ends of the cylinder body are respectively fixed with the inner wall of the main valve body, a liquid outlet is formed in the surface of one side of the cylinder body, which is close to the water inlet cavity, a liquid inlet is formed in the surface of one side of the cylinder body, which is close to the water outlet cavity, a partition plate is fixedly arranged in the middle position inside the cylinder body, the water inlet check valve plate and the water outlet check valve plate are arranged in the cylinder body, the water inlet check valve plate is arranged on one side, which is close to the water inlet cavity, of the middle cavity, and the water outlet check valve plate is arranged on one side, which is close to the water outlet cavity, of the middle cavity;

the water inlet check valve plate is positioned at the inner side of the cylinder body and right opposite to the liquid outlet, the water inlet check valve plate is in clearance fit with the inner wall of the cylinder body, a first spring is connected between the water inlet check valve plate and the partition plate, a supporting disc is fixedly arranged at one side of the water inlet check valve plate, facing the partition plate, of the water inlet check valve plate, an annular first diaphragm is arranged between the water inlet check valve plate and the partition plate, one end of the first diaphragm is fixed with the water inlet check valve plate, and the other end of the first diaphragm is fixed with the partition plate;

the water outlet check valve plate is positioned at the inner side of the cylinder body and is opposite to the position of the liquid inlet, the water outlet check valve plate is in clearance fit with the inner wall of the cylinder body, a guide shaft opposite to the supporting disc is arranged at the center position of the water outlet check valve plate, the guide shaft and the cylinder body are coaxially arranged, the guide shaft is relatively fixed with the inner wall of the cylinder body, the water outlet check valve plate is in sliding fit with the guide shaft, a spring II is fixedly arranged between one end, close to the supporting disc, of the water outlet check valve plate and one end, close to the water outlet cavity, of the guide shaft, and a membrane II is fixedly arranged between the outer surface of the water outlet check valve plate and one end, close to the water outlet cavity, of the cylinder body.

Optionally, the water inlet check valve plate comprises a sealing plate opposite to the water inlet cavity and a guide sleeve positioned in the cylinder body, wherein the sealing plate is fixedly connected with the guide sleeve, and the guide sleeve is in clearance fit with the inner wall of the cylinder body.

Optionally, the sealing plate is provided with the annular support sleeve I in the position department that is close to the uide bushing, and baffle just is provided with annular support sleeve II to the one side surface fixation of support sleeve I, and support sleeve I cover is located support sleeve external surface, and support sleeve I and support sleeve II be clearance fit.

Optionally, the supporting disk includes connection pad and butt post, and connection pad and closing plate face butt of one side that deviates from the intake chamber are fixed, and the butt post is fixed in connection pad orientation water outlet check valve plate's one side, and diaphragm one's one end inlays to be established and is fixed in between closing plate and the connection pad, and diaphragm one other end inlays to be established and is fixed in between baffle and the support cover two.

Optionally, a central bolt is arranged at the central position of the sealing plate in a penetrating way, and the central bolt is in threaded connection with the sealing plate.

Optionally, the water outlet check valve plate comprises a liquid inlet plugging plate, a connecting column and a linkage part, wherein the liquid inlet plugging plate is positioned at a position which is just opposite to the liquid inlet in the cylinder body and is in clearance fit with the inner wall of the cylinder body, the linkage part is sleeved on the surface of the guide shaft and is in sliding fit with the guide shaft, and two ends of the connecting column are respectively fixed with the liquid inlet plugging plate and the linkage part.

Optionally, a port ring is fixedly arranged at one end position of the guide shaft, which faces the water outlet cavity, and two ends of the second spring are respectively fixed with the linkage part and the port ring.

Optionally, the one end that the inlet shutoff board faced the water outlet chamber is installed the clamp plate through the bolt, and the cylinder body is close to the one end outer wall of water outlet chamber and is installed and compress tightly the packing ring, and the top of diaphragm two is fixed in between clamp plate and the inlet shutoff board tip, and the bottom of diaphragm two is compressed tightly between packing ring and main valve body inner wall.

Optionally, the liquid inlet plugging plate is provided with a step of stepping down on the surface of one side opposite to the liquid inlet, the step of stepping down extends along the direction facing the water outlet cavity, and the folding part of the second diaphragm is positioned in the step of stepping down.

Optionally, the cylinder body is provided with lock nut in the position of the one end outer wall that is close to the water cavity, lock nut and main valve body inner wall threaded connection, and lock nut compresses tightly the packing ring in the main valve body inner wall.

By adopting the technical scheme, when water is normally supplied, the water inlet check valve can be opened only by overcoming the elastic force of the first spring when the water pressure of the water inlet cavity pushes away the valve plate of the water inlet check valve, and meanwhile, the valve plate of the water outlet check valve is pushed to move towards the direction of the water outlet cavity by the abutting column on the supporting disc, a medium flows to the water outlet cavity, the low-resistance backflow preventer normally supplies water, the sealing ring resistance is avoided in the whole opening process, and the head loss can be greatly reduced; once the pressure of the water outlet cavity is increased, the water pressure of the water outlet cavity is reacted on the back surface of the water inlet check valve plate, the water inlet check valve plate is closed first, and meanwhile, the water outlet check valve plate closes the liquid inlet under the action of the spring II, so that backflow is avoided.

Optionally, the top of the first diaphragm is tightly fixed between the sealing plate and the supporting plate, the bottom of the first diaphragm is fixed on the surface of one side of the partition plate, which faces the water inlet cavity, through bolts, and the first diaphragm is made of a surface tension material.

In summary, the application has the following technical effects:

1. the outer diameter of the water inlet check valve plate and the outer diameter of the water outlet check valve plate are in clearance fit with the inner diameter of the cylinder body, and the two-stage check valve plates can freely and smoothly slide in the cylinder body;

2. one end of the first diaphragm is fixed at one end, close to the water inlet, of the middle partition plate of the cylinder body by utilizing the second support sleeve, the other end of the first diaphragm is flatly paved on the support disc and is fixedly connected with the valve plate of the water inlet check valve, the largest outer circle of the first support sleeve is matched with the inner diameter of the valve plate of the water inlet check valve, the first support sleeve slides relatively to the second support sleeve, the first support sleeve is in clearance fit with the second support sleeve, and the sliding resistance is reduced while the tightness is ensured;

3. one end of the diaphragm II is fixed at one end of the valve plate of the water outlet check valve, which is close to the water outlet cavity, and the other end of the diaphragm II is embedded into the U-shaped groove of the compression gasket, and a step is arranged on the surface of one side, which is opposite to the liquid inlet, of the liquid inlet plugging plate, so that the diaphragm II can play a role in sealing, excessive friction with the liquid inlet plugging plate is avoided, and the smoothness of sliding is maintained;

4. the first support sleeve and the second support sleeve can limit the deformation of the first membrane, and the first membrane is protected from being damaged due to single-sided compression in a backflow state.

Drawings

FIG. 1 is a schematic cross-sectional view of a membrane-type low-resistance backflow preventer in embodiment 1 of the present application;

FIG. 2 is a schematic view showing the structure of a check valve body in embodiment 1 of the present application;

FIG. 3 is an enlarged schematic view of a portion of FIG. 1 at A;

FIG. 4 is an enlarged partial schematic view at B in FIG. 1;

fig. 5 is a schematic view showing a state of the membrane type low resistance backflow preventer in embodiment 1 of the present application when normally supplying water;

fig. 6 is a schematic view showing a state in which the membrane backflow preventer of embodiment 1 of the present application is back flowed;

fig. 7 is a schematic view showing the structure of a check valve body when the back flow of the diaphragm type backflow preventer in embodiment 2 of the present application;

fig. 8 is a schematic view showing the structure of a check valve body in the case of the diaphragm type backflow preventer of embodiment 2 of the present application when water is normally supplied.

In the figure, 1, a main valve body; 11. a water inlet cavity; 12. an intermediate chamber; 13. a water outlet cavity;

2. a check valve body; 21. a cylinder; 211. a liquid inlet; 212. a liquid outlet; 213. a rubber cushion I; 214. a valve seat; 215. a mounting plate; 22. a water inlet check valve plate; 221. a sealing plate; 222. a guide sleeve; 2221. filling the corners; 23. a water outlet check valve plate; 231. a liquid inlet plugging plate; 2311. plugging the pointed end; 2312. a step of giving way; 232. a connecting column; 233. a linkage part; 2331. a second spring;

3. a first supporting sleeve; 31. a bottom ring; 311. a first spring; 32. a collar;

4. a second supporting sleeve;

5. a partition plate; 51. rubber cushion pressing strips; 52. a second rubber cushion; 53. a connecting body;

6. a support plate; 61. a connecting disc; 611. a center bolt; 612. a gasket; 62. abutting the column;

7. a first membrane;

8. a second membrane;

9. a guide shaft; 91. a port ring;

10. a pressing plate; 101. compressing the gasket; 102. and (5) locking the nut.

Detailed Description

The present application will be described in further detail with reference to the accompanying drawings.

Example 1

Referring to fig. 1 and 2, the diaphragm type low-resistance backflow preventer provided by the application comprises a main valve body 1 and a check valve body 2 arranged in the main valve body 1, wherein a water inlet cavity 11, a middle cavity 12 and a water outlet cavity 13 which are sequentially communicated are arranged in the main valve body 1, the cross section size of the middle cavity 12 is larger than that of the water inlet cavity 11 and the water outlet cavity 13, the check valve body is arranged in the middle cavity 12, and the check valve body is mainly used for preventing water flow in the water outlet cavity 13 from flowing back into the water inlet cavity 11.

The check valve body 2 includes cylinder body 21, intake check valve plate 22 and play water check valve plate 23, and cylinder body 21 is inside cavity, the ring structure that both ends link up, and cylinder body 21 sets up in middle chamber 12 and both ends closely laminate with the inner wall of main valve body 1, and a plurality of liquid outlets 212 have been seted up to the circumference of cylinder body 21 in the one side that is close to intake chamber 11, and a plurality of inlet 211 have been seted up to the circumference of cylinder body 21 in the one side that is close to play water chamber 13, and liquid outlet 212 is used for communicating middle chamber 12 with intake chamber 11, and inlet 211 is used for communicating middle chamber 12 with play water chamber 13. The water inlet check valve plate 22 and the water outlet check valve plate 23 are both disposed inside the cylinder 21, and the water inlet check valve plate 22 is located at a position close to the water inlet chamber 11, and the water outlet check valve plate 23 is located at a position close to the water outlet chamber 13.

The water inlet check valve plate 22 comprises a sealing plate 221 and a guide sleeve 222, the sealing plate 221 is arranged opposite to the water inlet cavity 11, the guide sleeve 222 is fixed with the circumferential position of the sealing plate 221, the guide sleeve 222 is arranged at the position opposite to the liquid outlet 212, when water flows into the water inlet cavity 11, the water flow pressure can push the sealing plate 221 to move horizontally, the sealing plate 221 drives the guide sleeve 222 to translate and open the liquid outlet 212, and therefore water flow of the water inlet cavity 11 can flow into the middle cavity 12 from the liquid outlet 212.

A supporting disc 6 is arranged on the surface of one side, away from the water inlet cavity 11, of the sealing plate 221, the supporting disc 6 comprises a connecting disc 61 and an abutting column 62, the connecting disc 61 covers the surface of the sealing plate 221, the connecting disc 61 and the sealing plate 221 are fixed through a central bolt 611, and a gasket 612 for sealing is arranged between a nut of the central bolt 611 and the sealing plate 221; the abutment posts 62 are provided in plurality and fixed to the side of the connection plate 61 facing the water outlet chamber 13.

The whole support disc 6 is arranged between the water inlet check valve plate 22 and the water outlet check valve plate 23 and is used for driving the water outlet check valve plate 23 to move while the water inlet check valve plate 22 moves.

One side surface fixing that closing plate 221 deviates from intake cavity 11 is provided with support cover one 3, and support cover one 3 is located closing plate 221 and is close to the position department of liquid outlet 212, and support cover one 3 is located the one side that guide sleeve 222 deviates from liquid outlet 212, support cover one 3 and cylinder body 21 inner wall be clearance fit. The fixed baffle 5 that is provided with in cylinder body 21 inner wall intermediate position department, baffle 5 set up between inlet 211 and liquid outlet 212, and baffle 5 center is hollow form for the butt post 62 of supporting disk 6 to pass, and baffle 5 is provided with support cover two 4 towards the one side fixed surface of inlet chamber 11, and support cover two 4 cover is located support cover one 3 inside and is clearance fit with support cover one 3, and support cover two 4 forms fixedly with baffle 5 through a plurality of bolts.

The first support sleeve 3 comprises a bottom ring 31 and a collar 32, the bottom ring 31 is fixedly arranged on the surface of the sealing plate 221, the collar 32 is fixedly arranged on the bottom ring 31, the collar 32 extends towards the water outlet cavity 13, more specifically, the second support sleeve 4 is sleeved inside the collar 32 and is in sliding connection with the collar 32, and the second support sleeve 4 is in clearance fit with the collar 32.

A first spring 311 is arranged between the partition plate 5 and the bottom ring 31, two ends of the first spring 311 are respectively fixed with the bottom ring 31 and the partition plate 5, when the first spring 311 is in a natural state, the sealing plate 221 is attached to the inner wall of the cylinder 21, which is close to the water inlet cavity 11, and the guide sleeve 222 just shields the liquid outlet 212 to form a seal; when the water inlet cavity 11 is filled with water, the water pressure of the water inlet cavity 11 is increased, the water pressure pushes the sealing plate 221 to translate, the first spring 311 is pressed, the guide sleeve 222 is driven to open the liquid outlet 212, and water flows from the water inlet cavity 11 into the middle cavity 12.

The first diaphragm 7 is clamped and fixed between the connecting disc 61 and the sealing plate 221, the bottom of the first diaphragm 7 is fixed at one end, close to the liquid inlet 211, of the middle partition plate of the cylinder body 21 by the second supporting sleeve 4, the top of the first diaphragm 7 is flatly paved on the connecting disc 61 of the supporting disc 6, the first diaphragm 7 is made of a material with certain elasticity, such as rubber, and because a plurality of positions between the water inlet check valve plate 22 and the cylinder body 21 are in clearance fit, the sliding fit between the water inlet check valve plate 22 and the cylinder body 21 is smoother, the friction loss is reduced, and meanwhile the sealing is further enhanced by the first diaphragm 7, so that the set effect is achieved.

Referring to fig. 2 and 3, further, a valve seat 214 is fixedly disposed on the inner wall of the cylinder 21 at a position close to one end of the water inlet chamber 11, a mounting plate 215 is fixed on a side surface of the valve seat 214 facing away from the water inlet chamber 11 through bolts, a cavity is reserved at a joint of the valve seat 214 and the mounting plate 215, a first rubber pad 213 is filled in the cavity, the first rubber pad 213 is fixedly clamped by the mounting plate 215 and the valve seat 214, the first rubber pad 213 is located at a position, close to the liquid outlet 212, of the inner side of the cylinder 21 and facing the guide sleeve 222, a gap filling angle 2221 with an inclined end is disposed at a position, facing the guide sleeve 222, of the end of the first rubber pad 213, and in a non-water-passing state, the gap filling angle 2221 abuts against the surface of the first rubber pad 213 to form a deep seal.

In this embodiment, a guide shaft 9 is installed at the center of the partition 5, the guide shaft 9 is fixedly connected to the cylinder 21 and is coaxially disposed, and the guide shaft 9 is internally penetrated. The water outlet check valve plate 23 comprises a liquid inlet plugging plate 231, a connecting column 232 and a linkage part 233, wherein the liquid inlet plugging plate 231 is arranged inside the cylinder 21 and is opposite to the liquid inlet 211, so as to be used for plugging the liquid inlet 211, the liquid inlet plugging plate 231 is in clearance fit with the inner wall of the cylinder 21, the linkage part 233 is sleeved on the guide shaft 9 and is in sliding fit with the guide shaft 9, one end of the connecting column 232 is fixed with the liquid inlet plugging plate 231, and the other end of the connecting column 232 is fixed with the linkage part 233. The end of the abutment post 62 abuts against the surface of the linkage 233 to push the entire water outlet check valve plate 23 to move synchronously by the abutment post 62 while the water inlet check valve plate 22 moves.

Further, a port ring 91 is fixedly arranged at one end of the guide shaft 9, which is close to the water outlet cavity 13, a second spring 2331 is arranged between the port ring 91 and the linkage part 233, one end of the second spring 2331 is fixed with the linkage part 233, the other end of the second spring 2331 is fixed with the port ring 91, and the elastic force of the second spring 2331 is smaller than that of the first spring 311.

Referring to fig. 2 and 4, the liquid inlet plugging plate 231 is provided with a pressing plate 10 at one end close to the water outlet cavity 13, the pressing plate 10 is fixed with the liquid inlet plugging plate 231 through bolts, a second diaphragm 8 is fixedly pressed between the pressing plate 10 and the liquid inlet plugging plate 231, the second diaphragm 8 is made of elastic materials such as rubber, the cylinder 21 is provided with a pressing washer 101 at the outer wall position close to one end of the water outlet cavity 13, the pressing washer 101 is fixed with the inner wall of the main valve body 1 through a locking nut 102, one side of the pressing washer 101 facing the inner wall of the main valve body 1 is provided with a U-shaped groove, the bottom of the second diaphragm 8 is pressed in the U-shaped groove, and when the pressing washer 101 is tightly attached to one end of the main valve body 1, the locking nut 102 tightly attaches the other end of the cylinder 21 to the other end of the main valve body 1 through threads on the cylinder 21, and sealing is ensured.

Furthermore, the liquid inlet plugging plate 231 is provided with a step 2312 facing the liquid inlet 211, the step 2312 extends towards the water outlet cavity 13, the second diaphragm 8 is folded and arranged inside the step 2312, when the water outlet check valve plate 23 is pushed to move by the water inlet check valve plate 22, the movement of the water outlet check valve plate 23 is smoother due to the clearance fit between the liquid inlet plugging plate 231 and the inner wall of the cylinder 21, and meanwhile the second diaphragm 8 can assist in strengthening the sealing effect, so that the condition of loose sealing caused by the clearance fit is avoided, meanwhile, the second diaphragm 2312 has enough folding and extending space, the second diaphragm 8 is effectively prevented from being excessively extruded and deformed, and the normal use of the second diaphragm 8 is ensured.

The baffle 5 is at the one side surface towards water cavity 13 through bolt fixedly connected with cushion layering 51, and cushion layering 51 compresses tightly a cushion second 52 and is fixed in baffle 5 surface, and cushion second 52 is located the position department of just being to inlet shutoff board 231, more specifically is provided with shutoff pointed end 2311 at the tip that inlet shutoff board 231 is towards cushion second 52, when spring second 2331 is in former length state, shutoff pointed end 2311 butt is at cushion second 52 surface to make the sealed effect of inlet 211 department when idle.

The specific implementation principle of the embodiment of the application is as follows: when water is normally supplied, as shown in fig. 5, the water pressure of the water inlet cavity 11 acts on the sealing plate 221, the sealing plate 221 moves horizontally, the first compression spring 311 drives the guide sleeve 222 to open the liquid outlet 212, the liquid enters the middle cavity 12 from the water inlet cavity 11, meanwhile, the sealing plate 221 moves together with the supporting disc 6 in the pushed process, the abutting column 62 of the supporting disc 6 pushes the linkage part 233 of the water outlet check valve plate 23, the second compression spring 2331 drives the liquid inlet blocking plate 231 to translate through the connecting column 232, the liquid inlet 211 is opened, the liquid enters the water outlet cavity 13 from the middle cavity 12 again, normal water supply is completed, the opening process of the check valve body 2 has no sealing ring resistance, and the water head loss is greatly reduced.

When the pressure of the water outlet cavity 13 rises, as shown in fig. 6, the two-stage check valve plates are rapidly closed under the action of respective springs, specifically: after the pressure of the water outlet cavity 13 increases, the outlet pressure acts against the supporting disc 6, the first auxiliary spring 311 pushes the water inlet check valve plate 22 to move towards the water inlet cavity 11, the end part of the guide sleeve 222 of the water inlet check valve plate 22 is ensured to be abutted against the first rubber pad 213, and meanwhile, under the elastic restoring force of the second spring 2331, the plugging tip 2311 at the end part of the liquid inlet plugging plate 231 is abutted against the surface of the second rubber pad 52, so that the plugging of the liquid inlet 211 and the liquid outlet 212 is realized, and the liquid backflow is avoided.

Example 2

This embodiment differs from embodiment 1 in that:

referring to fig. 7 and 8, the first diaphragm 7 is thickened, the first diaphragm 7 has a certain surface tension, the top of the first diaphragm 7 is clamped and fixed between the sealing plate 221 and the connecting disc 61 through a central bolt 611, a connecting body 53 is fixedly arranged on one side surface of the partition plate 5 facing the water inlet cavity 11 through a bolt, the connecting body 53 is located at a position of the partition plate 5 close to the inner wall of the cylinder body, and the bottom of the first diaphragm 7 is fixedly arranged on the surface of the connecting body 53 through a bolt. When the liquid outlet 212 is in an open state, the first diaphragm 7 is in a normal state, the tension of the first diaphragm 7 needs to be overcome when the valve plate 22 of the water inlet check valve is closed, and the opening is not influenced by the resistance of the first diaphragm 7.

The present embodiment is only for explanation of the present application and is not to be construed as limiting the present application, and modifications to the present embodiment, which may not creatively contribute to the present application as required by those skilled in the art after reading the present specification, are all protected by patent laws within the scope of claims of the present application.

Claims (10)

1. A diaphragm type low resistance backflow preventer is characterized in that: comprising the following steps:

the main valve comprises a main valve body (1), wherein a water inlet cavity (11), a middle cavity (12) and a water outlet cavity (13) which are sequentially communicated are arranged in the main valve body (1), and the cross section size of the middle cavity (12) is larger than that of the water inlet cavity (11) and the water outlet cavity (13);

the check valve body (2), check valve body (2) include cylinder body (21), intake check valve plate (22) and play water check valve plate (23), cylinder body (21) are installed in middle chamber (12), and cylinder body (21) both ends are fixed with main valve body (1) inner wall respectively, liquid outlet (212) have been seted up to one side surface that cylinder body (21) is close to intake chamber (11), intake (211) have been seted up to one side surface that cylinder body (21) is close to play water chamber (13), fixed baffle (5) that are provided with in the inside intermediate position department of cylinder body (21), intake check valve plate (22) and play water check valve plate (23) are installed in cylinder body (21), and intake check valve plate (22) are installed in one side that middle chamber (12) is close to intake chamber (11), play water check valve plate (23) are installed in one side that middle chamber (12) is close to play water chamber (13).

The water inlet check valve plate (22) is positioned at the inner side of the cylinder body (1) and is opposite to the liquid outlet (212), the water inlet check valve plate (22) is in clearance fit with the inner wall of the cylinder body (21), a first spring (311) is connected between the water inlet check valve plate (22) and the partition plate (5), a supporting disc (6) is fixedly arranged at one side position of the water inlet check valve plate (22) facing the partition plate (5), an annular first diaphragm (7) is arranged between the water inlet check valve plate (22) and the partition plate (5), the top of the first diaphragm (7) is fixed with the water inlet check valve plate (22), and the bottom of the first diaphragm (7) is fixed with the partition plate (5);

the water outlet check valve plate (23) is located at the inner side of the cylinder body (1) and is right opposite to the position of the liquid inlet (211), the water outlet check valve plate (23) is in clearance fit with the inner wall of the cylinder body (21), a guide shaft (9) right opposite to the supporting disc (6) is arranged at the center of the water outlet check valve plate (23), the guide shaft (9) and the cylinder body (21) are coaxially arranged, the guide shaft (9) and the inner wall of the cylinder body (21) are relatively fixed, the water outlet check valve plate (23) is in sliding fit with the guide shaft (9), a spring II (2331) is fixedly arranged between one end, close to the supporting disc (6), of the water outlet check valve plate (23) and one end, close to the water outlet cavity (13), of the guide shaft (9), and a diaphragm II (8) is fixedly arranged between the outer surface of the water outlet check valve plate (23) and one end, close to the water outlet cavity (13), of the cylinder body (21).

2. The diaphragm type low-resistance backflow preventer according to claim 1, wherein: the water inlet check valve plate (22) comprises a sealing plate (221) opposite to the water inlet cavity (11) and a guide sleeve (222) positioned in the cylinder body, the sealing plate (221) is fixedly connected with the guide sleeve (222), and the guide sleeve (222) is in clearance fit with the inner wall of the cylinder body (21).

3. The diaphragm type low-resistance backflow preventer according to claim 2, wherein: the sealing plate (221) is fixedly provided with a first annular supporting sleeve (3) at a position close to the guide sleeve (222), a second annular supporting sleeve (4) is fixedly arranged on one side surface of the first annular supporting sleeve (3) opposite to the baffle plate (5), the first annular supporting sleeve (3) is sleeved on the outer surface of the second annular supporting sleeve (4), and the first annular supporting sleeve (3) and the second annular supporting sleeve (4) are in clearance fit.

4. A diaphragm type low resistance backflow preventer according to claim 3, wherein: the supporting plate (6) comprises a connecting plate (61) and a butt column (62), the connecting plate (61) is fixed with a side surface of the sealing plate (221) deviating from the water inlet cavity (11) in a butt mode, the butt column (62) is fixed on one side, facing the water outlet check valve plate (23), of the connecting plate (61), the top of the first membrane (7) is embedded and fixed between the sealing plate (221) and the connecting plate (61), and the bottom of the first membrane (7) is embedded and fixed between the partition plate (5) and the second supporting sleeve (4).

5. The diaphragm type low-resistance backflow preventer according to claim 1, wherein: the water outlet check valve plate (23) comprises a liquid inlet plugging plate (231), a connecting column (232) and a linkage part (233), wherein the liquid inlet plugging plate (231) is positioned in the cylinder body (21) and is opposite to the liquid inlet (211) and in clearance fit with the inner wall of the cylinder body (21), the linkage part (233) is sleeved on the surface of the guide shaft (9) and is in sliding fit with the guide shaft (9), and two ends of the connecting column (232) are respectively fixed with the liquid inlet plugging plate (231) and the linkage part (233).

6. The diaphragm type low-resistance backflow preventer of claim 5, wherein: a port circular ring (91) is fixedly arranged at one end position of the guide shaft (9) facing the water outlet cavity (13), and two ends of the spring II (2331) are respectively fixed with the linkage part (233) and the port circular ring (91).

7. The diaphragm type low-resistance backflow preventer of claim 5, wherein: the one end that inlet shutoff board (231) was towards play water cavity (13) is installed clamp plate (10) through the bolt, and compression washer (101) are installed to the one end outer wall that cylinder body (21) is close to play water cavity (13), and the top of diaphragm two (8) is fixed in between clamp plate (10) and inlet shutoff board (231) tip, and the bottom of diaphragm two (8) is compressed tightly between compression washer (101) and main valve body (1) inner wall.

8. The diaphragm type low-resistance backflow preventer of claim 7, wherein: the liquid inlet plugging plate (231) is provided with a yielding step (2312) on the surface of one side opposite to the liquid inlet (211), the yielding step (2312) extends along the direction facing the water outlet cavity (13), and the folding part of the second diaphragm (8) is positioned in the yielding step (2312).

9. A diaphragm type low resistance backflow preventer according to claim 7 or 8, wherein: the cylinder body (21) is provided with a lock nut (102) at the outer wall position of one end close to the water outlet cavity (13), the lock nut (102) is in threaded connection with the inner wall of the main valve body (1), and the lock nut (102) compresses the compression washer (101) in the main valve body (1).

10. A diaphragm type low resistance backflow preventer according to claim 1 or 2, wherein: the top of the first membrane (7) is pressed and fastened between the sealing plate (221) and the supporting plate (6), the bottom of the first membrane is fixed on one side surface of the partition plate (5) facing the water inlet cavity (11) through bolts, and the first membrane (7) is made of a membrane (7) made of a surface tension material.